A bullet of mass embeds itself in a wooden block of mass that is initially at rest
PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A bullet of mass m embeds itself in a wooden block of mass M that is initially at rest.
• Scenario I: The block rests on a frictionless horizontal surface.
• Scenario II: The block rests on a horizontal surface that exerts significant kinetic friction.
During the very short time interval in which the bullet comes to rest inside the block, which statement correctly describes the conservation of linear momentum for the bullet–block system?
(a) Momentum is conserved in both scenarios because friction acts only after the bullet stops.
(b) Momentum is not conserved in either scenario because the bullet experiences a non-zero force while stopping.
(c) Momentum is conserved in Scenario I but not in Scenario II because the friction force on the block is external during the interval.
(d) Momentum is conserved in Scenario II but not in Scenario I because the kinetic energy loss in Scenario II is greater.